The present invention relates generally to semiconductor device packages, and more particularly to magnetic shielded semiconductor device packages.
Magnetic materials are used in a variety of semiconductor devices such as magnetic cell memories and magnetic field sensors. Magnetic random access memory (MRAM) devices are being explored for use as non-volatile solid state memory devices for embedded and stand alone applications. Typically MRAM devices utilize magnetic material within memory cells to store data bits.
MRAM devices may be subject to error in the presence of stray or externally applied electromagnetic fields other than applied write fields. Such stray fields can originate from a variety of sources including other electronic devices such as computers, displays, etc. and may have sufficient magnitude to switch the logic state of one or more memory cells even in the absence of a write field.
One way of protecting the MRAM devices from the external environment is by encapsulation with an epoxy material or transfer molding a thermoplastic resin around the device. However, the epoxy or plastic encapsulent does not provide effective shielding from radiation such as EMI or RFI.
Other systems use magnetic shielding materials to shield the device from magnetic fields. FIG. 1 is a cross-sectional view of a conventional ball grid array package 10 having a MRAM die 12. The MRAM die 12 is attached to and electrically coupled to a substrate 14 with wires 16. The wires 16 are bonded to corresponding pads 18 on the substrate using a well known wire bonding process.
A magnetic shield 20 is attached to a top surface of the MRAM die 12. The magnetic shield 20 may include a traditional Ni/Fe shield for protecting the MRAM die 12 from external magnetic fields. An encapsulating material 22 such as epoxy molding compound covers the substrate 14, the MRAM die 12 and the magnetic shield 20. The package 10 also includes solder balls 22 attached to the substrate 14 for providing external electrical interconnection.
However, as can be seen, the magnetic shield 20 provides protection to only one side of the die 12, while the other side is still susceptible to stray magnetic waves. Therefore a need exists for a semiconductor package with enhanced magnetic resistance.